1. Technical Field
The invention relates to an eye tracking system. Particularly, the invention relates to a head-mount eye tracking system.
2. Related Art
Presently, an eye tracking technique is mainly divided into a contact eye tracking technique that requires contacting the eye and a non-contact eye tracking technique without contacting the eye. The contact eye tracking technique mainly includes a search-coil (SC) method and an electro-oculography (EOG) method, and the non-contact eye tracking technique mainly includes a free-head eye tracking technique and a head-mount eye tracking technique.
Regarding the contact eye tracking technique, taking the SC method as an example, a user is required to wear contact lenses having sensing coils. When the user rotates eyeballs to drive the lenses, the sensing coils produce an induced electromotive force (EMF) due to variation of a magnetic flux, and a magnitude of the EMF represents a deflection angle of the eyeball. Regarding the EOG method, a plurality of electrodes are attached around the eye, and the electrodes are used to detect a voltage difference generated by the eyeball rotation to determine the deflection angle of the eyeball. A disadvantage of the contact eye tracking technique is that contact of a foreign matter may cause strong eye discomfort, and eye and/or skin secretions may cause signal interference.
Regarding the free-head eye tracking technique, an eye tracker with a screen and dual image capturing devices is developed. However, the existing free-head eye tracking technique is still required to resolve a problem of errors caused by movement of user's head. Moreover, the free-head eye tracking technique also has disadvantages of complex in operation and high cost, etc.
Comparatively, regarding the head-mount eye tracking technique, an image capturing device and a light source are mounted on user's head, and a pupil image captured by the image capturing device is used to deduce a gazing position, which may eliminate the error caused by movement of the user's head. Therefore, the head-mount eye tracking system can be widely applied in industries of biomedicine, medical treatment, transportation and entertainment, etc. However, since the existing head-mount eye tracking technique determines the gazing position of the user only according to the eye information (the pupil image), it is easy to make a wrong determination. Moreover, the existing head-mount eye tracking technique generally has a problem that a sight line is shielded by the head-mount eye tracking system, which causes inconvenience in utilization.